MOSCOW, July 15. /TASS/. Talks between Russian President Vladimir Putin and US State Secretary were constructive and detailed, but questions remain on cooperation between the two countries on Syria, Kremlin spokesman Dmitry Peskov told reporters on Friday.

"Talks were continued, they were rather constructive, rather honest and detailed," Peskov said adding that the meeting ended well after midnight.

However, "many questions remain connected with real cooperation during the operation in Syria," he noted.

John Kerry has confirmed his talks with Vladimir Putin were "extremely frank and very serious."

Direct cooperation of Russian and US military

The topic of direct interaction between the Russian and the US military in Syria was not discussed at the meeting of the top officials.

"They discussed different cooperation formats, but the topic of direct cooperation between the military in combating terrorism in Syria was not mentioned," Peskov said.

According to him, the exchange of information in this area "is present, but still, unfortunately, we are not much closer to real cooperation in order to increase the effectiveness of efforts to combatting terrorism in Syria."

Russia’s stance on Assad’s fate

According to Peskov, Russia’s stance on the fate of Syrian President Bashar al-Assad at the talks with John Kerry has remained unchanged.

"As for Assad’s fate, Russia’s well-known position has not undergone any changes," he said.

Peskov noted that Russia favors the continuation of the talks on the Syrian settlement, adding that the political solution to this crisis is only possible by means of continuing the Geneva process.

Peskov declined to comment on whether the two sides had made any progress at the talks. "I said everything I wanted on the issue," he said. "The main assessments will be made by [Russian Foreign] Minister [Sergey] Lavrov and [US] Secretary of State [John] Kerry."

START treaty extension

The sides held no discussions over the extension of the START treaty.

"No," Peskov said answering the question whether Kerry had raised this issue during yesterday’s talks with Putin.